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Biomedical subjects

L Drobnica

Publications and source records attributed to L Drobnica.

At least 19 recordsLinked to original sources
PubMed1979

The reaction of carbonyl cyanide phenylhydrazones with thiols.

Carbonyl cyanide phenylhydrazone and its ring-substituted analogs react with thiols (thioglycolic acid, 2-mercaptoethanol, dithiothreitol) and aminothiols (cysteine, glutathione) to give corresponding N-(substituted phenyl)-N'-(alkylthiodicyano)-methylhydrazine derivatives. These addition products decompose to the original components in alkaline solution. On the other hand, in the presence of an excess of thiols in aqueous buffered systems the addition reactions are practically quantitative with respect to phenylhydrazones, follow pseudo-first-order kinetics and can be investigated spectrophotometrically. These reactions are of the bimolecular AdN type where the non-dissociated form of carbonyl cyanide phenylhydrazones function as an electrophilic component, while the RS- ion plays the role of nucleophilic component in the case of thiols (the attack of the azomethine group). The reactivitiy of carbonyl cyanide phenylhydrazones with respect to thiols increases in the order carbonyl cyanide phenylhydrazone less than carbonyl cyanide m-chlorophenylhyrazone less than carbonyl cyanide p-trifluoromethoxyphenylhydrazone which corresponds to the order of decreasing values of the pKa constants. On the other hand, the reactivity of thiols increases with their basicity. The reactivity of carbonyl cyanide phenylhydrazone with thiols is comparable with the reactivity of phenyl isothiocyanate and N-ethylmaleimide. It was demonstrated that carbonyl cyanide phenylhydrazone is an efficient inhibitor of rabbit muscle glyceraldehyde-3-phosphate dehydrogenase (EC 1.2.1.12). The results obtained are discussed in relation to the biological activity of carbonyl cyanide phenylhydrazones.

Animals↗
PubMed1979

Effect of glycerol on viability and other properties of starved Mycobacterium fortuitum.

Cells of Mycobacterium fortuitum kept in 0.85% saline solution containing 0.1% Tween 80 (without glycerol) survive for a long time. In glycerol-enriched medium, they continue to lose their viability at a high rate; after 71 days of exposure the percentage of survival as indicated by colony formation and respiratory and dehydrogenase activities is lower than 1%. Surviving cells starved in medium without glycerol revealed unchanged sensitivity to streptomycin, p-aminosalicylic acid, and isoniazid.

Antitubercular Agents↗
PubMed1979

Effect of chloro- and bromo-derivatives of isocrotonic acid of bioenergetic processes in Ehrlich ascites cells and isolated mitochondria.

The effect of nine chloro- and bromoderivatives of isocrotonic acid on some bioenergetic processes in both Ehrlich ascites cells and isolated rat liver mitochondria has been investigated. Substances studied in the concentration range 25--200 microM significantly inhibited incorporation of both 14C-adenine and 14C-valine into acid-insoluble material of Ehrlich ascites cells. The rate of 14C-precursors incorporation being directly related to the concentration of the inhibitor. Gamma,gamma-bis-4-ethylphenyl-alpha,beta-dichloroisocrotonic acid fully inhibits both aerobic glucose utilization and lactic acid formation at 200 microM concentration. At lower concentrations, however, glycolysis is stimulated. Maximal stimulation of rat liver mitochondrial respiration in state 4 with succinate as substrate was reached at concentrations as low as 10 microM. On the other hand, these substances were able to release by the oligomycin inhibited respiration of rat liver mitochondria. Our data suggest that cytotoxic and cancerostatic action of isocrotonic acid derivatives lies primarily in the exclusion of key processes in the energy metabolism of Ehrlich ascites cells and isolated mitochondria.

Animals↗
PubMed1978

Cytotoxic and cancerostatic effect of 1,4-dithiaanthraquinone-2,3-dicarbonitrile.

1,4-Dithiaanthraquinone-2,3-dicarbonitrile (DTA) has been found to exert a considerable cytostatic effect especially on some of the investigated types of eukaryotic cells, concretely on the HeLa cells, moulds, yeasts, protozoa and algae. In cells of the Ehrlich ascites carcinoma (EAC) DTA after a short exposition causes a parallel inhibition of incorporation of 14C-adenine and 14C-valine, in proportion to its rising concentration. The inhibition of biosynthetic processes thus made manifest, is probably a consequence of the primary DTA intervention into the energy metabolism of EAC cells, particularly in glycolysis. The effect of DTA in concentrations capable of bringing about full inhibition of glucose consumption or lactate formation in EAC cells also results in a loss of their transplantability. On the other hand, DTA also exerts a cancerostatic effect on the Ehrlich ascites carcinoma in mice.

Animals↗
PubMed1977

Reactions of cellulose isothiocyanates with thiol and amino compounds.

A cellulose isothiocyanate has been prepared by treatment of cellulose with 2,4-di-isocyanatotoluene followed by hydrolysis and reaction of the resulting amine with thiophosgene. The cellulose isothiocyanate was characterized by its binding capacity with respect to [14C]-glycine, [131 I]-human serum albumin, and 2-mercaptoethanol. An analytical method for binding capacity, based on reaction with [35 S]-alpha-toluenethiol, was developed. Because of the aromatic character of the NCS group of the cellulose isothiocyanate, the covalently bonded thiol can be quantitatively liberated.

Binding Sites↗